| Kosi | |
| Native Name: | कोसी अञ्चल[1] कोशी अञ्चल |
| Settlement Type: | Zone |
| Mapsize: | 300px |
| Subdivision Type: | Country |
| Subdivision Name: |  Nepal |
| Subdivision Type1: | Region |
| Seat Type: | Capital |
| Population As Of: | 2011 |
| Population Total: | 2,335,047 |
| Blank Name Sec1: | Main language(s) |
| Timezone: | Nepal Time |
| Utc Offset: | +5:45 |
Kosi or Koshi (Nepali: कोसी अञ्चल, Nepali: [[:ne:कोशी अञ्चल|कोशी अञ्चल]]) was one of the fourteen zones of Nepal until the restructure of zones to provinces. The headquarters of Kosi Zone was Biratnagar which was also its largest city. Other cities of Kosi Zone were Inaruwa, Dharan, Dhankuta, Jhumka, Duhabi, Tarahara and Itahari. Its main rivers were Arun, Tamor and Sapta Koshi.
Kosi was divided into six districts; since 2015 these districts have been redesignated as part of Province No. 1.
| District | Type | Headquarters | Since 2015 part of Province |
|---|---|---|---|
| Bhojpur | Hill | Bhojpur | Province No. 1 |
| Dhankuta | Hill | Dhankuta | |
| Morang | Terai | Biratnagar | |
| Sankhuwasabha | Mountain | Khandbari | |
| Sunsari | Terai | Inaruwa | |
| Terhathum | Hill | Myanglung |